Another vote for Federal Premium. I'm a big fan of the copper plated 00 buckshot. It patterns well, cycles reliably in the auto's i've tried it in (Browning A-5, Remington 11-87, and Spas-12).
If you want full power load, the Federal Premium comes in 3 different varieties for 2-3/4".... 9-pellet, copper plated, 1325fps (stock # P154 00)... 12-pellet, copper plated, 1280fps (stock # P156 00)... and 9-pellet, copper plated, 1325fps, with flight control wad (stock # PFC154 00) for tighter patterns at longer ranges. The first type is what I use... lucky for me, Wally Wolrd has them on sale right now for$2.50 per box of five.
Federal also has the "Tactical" series in a fullpower load, but it's still pretty uncommon to find it in mass quantities for sale to non-LE. Remington has nickel plated buckshot, but I've never tried it. It's too hard to find.